VEHICLE SECURITY SYSTEM

Abstract: A security system (21) for use with a vehicle having an internal combustion engine (10) which is controlled by a management system (11). The security system (21) includes a control circuit (22) which is used to suppress data signals to or from the management system (11) to prevent engine operation. The security system (21) may include a touch switch circuit (29) which when actuated causes the control circuit (22) to be placed in a mode permitting operation of the engine (10). The system (21) may also include a door opening sensitive circuit (31) which when actuated causes the engine (10) to cease operating.

Description: VEHICLE SECURITY SYSTEM Technical Field This invention relates to a security system and particularly to a system for reducing the incidence of theft of apparatus powered by internal combustion engines. Background Art Theft of vehicles is a common occurrence and many systems and products have been used in the past aimed at reducing such occurrences. Such systems and products have ranged from burglar alarms installed in the vehicle which are actuated when an attempt is made to break into the vehicle, to physical restraints on moving the vehicle such as steering wheel locks, gear lever locks or systems which activate the brakes of a vehicle. In most of the systems and products available, however, the vehicle can still be stolen if the theft prevention devices are circumvented. This can occur often because the thief, being experienced can "hot wire" the ignition circuit so that the engine may still be started and driven away. A further security risk which has arisen with motor vehicles is that known as "car jacking". This occurs when a vehicle which is driven by an authorised user is entered, for example through one of the passenger doors by an unauthorised user when, say the vehicle is stopped at traffic lights. In such instances the authorised user may be exposed to violence and possible theft of the vehicle. Summary of the Invention The present invention aims to overcome or alleviate the above disadvantages by providing a security system applicable primarily to vehicles having internal combustion engines which simply and effectively disables such engines and prevents their unauthorised starting. The present invention aims in a preferred aspect to provide a system which prevents unauthorised starting of an engine by "hot wiring". The present invention is particularly suitable for use with motor vehicles, however it may readily be applied to boats, motor cycles or other equipment powered by an internal combustion engine and thus the term "vehicle" used throughout the speci ication includes the aforementioned. The present invention also aims in a further preferred aspect to provide a security system which incorporates means to prevent or minimise the risks of "car-jacking". Other objects and advantages of the invention will become apparent hereunder. The present invention thus provides in one aspect a security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said security system including control circuit means having first and second states, said control circuit means in said first state inhibiting operation of said management system so as to prevent operation of said engine, control means for causing said control circuit means to be placed from said first state into said second state, said control circuit means in said second state enabling operation of said management system thereby allowing operation of said engine. The management system of the engine normally includes a number of data lines which receive data from various sensors around the engine such as sensors associated with the harmonic balancer and which supply data for control of various engine components including an igniter for providing ignition pulses to the vehicle spark plugs and in the case of a fuel injected vehicle, to fuel injectors for supplying fuel at desired intervals through the injectors. The security system of the invention operates on the data lines to either prevent signals being received by the management system, such as timing signals from the harmonic balancer or prevent signals being transmitted to the igniter or fuel injectors. The control circuit means includes first switch means which is connected, preferably by DC isolating circuit to one or more of the data lines. The switch means when the ignition switch is OFF is normally open but is closed by the control circuit means when the ignition switch is turned ON. This connects the data lines to the main supply via a DC isolating circuit to suppress the data signals by effectively sending back an equal and opposite signal to cancel the data signals. The control circuit means also has a third inoperative state, when the engine is not in operation and the ignition switch is OFF, the control circuit means being placed from its third state into its first state upon switching of the ignition switch to an ON position which supplies current to the control circuit means. The internal combustion engine includes a starter solenoid and the control circuit means in its third and first states suitably maintains the circuit between the ignition switch and starter solenoid open, the control circuit means closing the circuit between the ignition switch and the solenoid in its second state. For this purpose the control circuit means may include a second switch means in series between the starter solenoid and ignition switch, the second switch means being normally open but being closed when the control circuit means is in its second state. Preferably, an anti-hotwiring circuit is associated with the security system for preventing starting of the engine by hot wiring. Suitably, the anti-hotwiring circuit comprises capacitance means associated with the control circuit means for inhibiting operation of the management system by preventing or corrupting data input thereto or data output therefrom when the circuit means is in its first state. The anti-hot wiring circuit may include the first switch means which is connected to one or more of the data input or data output lines of the management system so as to prevent data being supplied to the management system, or transmitted from the management system. Preferably, the capacitance means of the anti-hot wiring circuit is in series with the first switch means and connected to the ignition switch or a supply line supplied by the ignition switch. Thus, if the ignition switch terminals are bridged to supply current to the ignition system, the first switch will close connecting the data lines through the capacitance means to the supply effectively providing an AC short to suppress the data signals. The switch means may comprise mechanical switches but preferably the switch means are semiconductor switches such as MOSFET switches. In one particularly preferred form, the control means comprises touch responsive switch means. In a further form, the control means comprises remote actuating means. The remote actuating means may include infra-red control means. Preferably the control circuit means includes timing circuit means which requires the touch pad to be touched for a predetermined period of time before the control circuit means operates to switch the respective switches and enable the ignition circuit. This thereby prevents operation in the event that the touch pad is inadvertently touched. The security system of the invention also suitably includes a circuit which may be actuated to prevent continued engine operation where unauthorised entry to the vehicle has occurred during normal vehicle operation. For this purpose, the control circuit means is connected to one or more of the door switches to sense opening thereof. A timing circuit is provided so as to cause the control circuit means to be placed in its first state a predetermined time after sensing of opening of the door. This then prevents engine operation. In yet a further aspect the present invention provides a security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said management system having a plurality of data lines, said security system including control circuit means connectable to at least one of said data lines, said control circuit means in a first state suppressing or corrupting information on said at least one of said data lines to prevent operation of said engine, touch sensitive circuit means operable to cause said control circuit means to be placed from said first state into a second state, said control circuit means in said second state permitting data to flow along said data line to thereby permit operation of said engine. In yet a further aspect the present invention provides a security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said security system including control circuit means having first and second states, said control circuit means in said first state inhibiting operation of said management system so as to prevent operation of said engine, said circuit means in said second state enabling operation of said management system thereby allowing operation of said engine, and means for sensing opening of a door of said vehicle to cause said control circuit means to be placed in said first state to prevent operation of said engine. Brief Description of the drawing In order that the invention may be more readily understood and put into practical effect, reference will now be made to the accompanying drawing which is a block diagram of a management controlled vehicle engine provided with security means according to a preferred embodiment of the present invention. Detailed Description of the Preferred Embodiment Referring to the drawings there is illustrated schematically a vehicle engine 10 having an associated management system 11 incorporates a computer or microprocessor and which includes a number of data lines comprising input lines 12 which are connected to various sensors and receptors around the engine 10, including for example a sensor connected to a harmonic balancer to provide timing signals. The management system 11 also includes data output lines 14 which are connected say to an igniter 15 which generates pulses for application to the engine spark plugs. The management system 11 may also be connected through the output data lines 14 to electronic fuel injectors 16 of the engine 10 to control operation thereof. Other sensors and receptors around the vehicle engine 10 provide various signals by which the management system 11 controls vehicle operation. As is conventional a starter motor 17 is provided for the starting of the engine 10, the starter motor 17 being controlled by a starter solenoid 18. A battery 19 is provided for supplying current to the starter solenoid 18 and motor 17 and other electrical components of the engine, application of current from the battery 19 being controlled by a ignition switch 20 which suitably is key operated. The security system 21 of the invention is also adapted to receive supply through the ignition switch 20 and is based around a control circuit 22 which in this embodiment includes a software programmed microprocessor 23. The microprocessor 23 however, may comprise a hardware wired circuit. The control circuit 22 includes a first normally opened switch 24 which is arranged to be connected in series between the ignition switch 20 and starter solenoid 18. The system additionally includes a further normally open switch 25 which is connected to a DC isolating circuit 26 which may include a capacitor and which may be connected through line 27 to one of the data lines 12 or 14, to or from the management system 11. A capacitor 28 is provided between the ignition switch 20 or a supply line connected to the ignition switch 20, and switch 25. The switches 24 and 25 are preferably semi conductor switches, such as MOSFETS, whose switching is controlled by the microprocessor 23, the microprocessor 23 to cause switching of the MOSFET switches applying pulses to their gates. The microprocessor 23 is also supplied through the ignition switch 24. Connected to the microprocessor 23 is a touch sensitive switch circuit 29 which includes a touch pad or terminal 30. Also connected to the microprocessor 23 is a door switch circuit 31 which is connected to one or more door switches 32 of the vehicle, the door switches 32 comprising the normal courtesy or interior light switches mounted on the door pillar. In use and if one attempts to start the vehicle engine 10 by normal switching on the ignition switch 20, no current will be applied to the starter solenoid 18 because the circuit is broken by the normally open switch 24. Turning the ignition switch 20 to its ON state will, however, supply current to the control circuit 22 of the system 21 and place same in an active mode. Supply to the control circuit 22 will also cause the normally open switch 25 to close. If the touch pad 30 is touched during the time that current is supplied to the circuit 22 of the system 21 in its active mode, so as to complete, through the skin of the user, a circuit to earth, a triggering signal will be generated to cause the switch 24 to close and the switch 25 to open. A time delay provided by the microprocessor 23 however, will require the pad 30 to be touched, say for two seconds before the switching pulses are sent to the switches 24 and 25. When the ignition switch 20 is then turned to its ignition state, current will flow to the starter solenoid 18 through the closed switch 24 and at the same time the switch 25 being opened will disconnect the data lines 12 or 14 from the control circuit 22 so as to permit data to be received by or transmitted to the management system 11. The engine 10 may thus be started. If, however, the ignition switch 20 is turned OFF, power will be removed from the circuit 22 so that the circuit 22 is deactivated causing the switches 24 and 25 to return to their non-operative attitude with the switches 21 and 22 open. It will thus be apparent, that the engine 10 cannot be started until and unless the above procedure is again adopted. If one attempts to start the engine merely using the ignition key, nothing will happen as the ignition switch 20 is isolated from the starter solenoid 18 by the open switch 24. If one attempts to start the engine by "hot wiring", the ignition switch 20 is usually bypassed so that current can be supplied to the starter solenoid 18 and thus the starter motor. This supply will also be available or provided to the control circuit 22 so that the switch 25 will close. When the starter motor 17 cranks the engine 10, the sensors associated with the engine 10 will attempt to send data signals to the management system 11 and the management system 11 will attempt to send data to the fuel injectors 16 and/or the igniter 15. The capacitor 28, however, connected to the supply and through the closed switch 25 and isolating circuit 26 to the data lines 12 or 14 will effectively suppress through the switch 22 the data signals transmitted by or received from the management system 11. The capacitor 34 thus provides an AC short to cancel the data signals. The isolating circuit 26 prevents DC passing to the data lines 12 or 14 and thus the management system 11 from the supply to which the capacitor 28 is connected. The touch pad 30 for the touch switch circuit 29 may comprise any metal part of the vehicle which is insulated from earth or alternatively any metal part mounted to the vehicle such as a screw, bolt, or emblem again insulated from earth and the remainder of the vehicle. Such a touch pad 30 may be provided by any conductive element which for example may be mounted to a vinyl panel within the vehicle. Operation of the circuit 29 relies on a circuit being made from the touch pad 30 to earth through the body. This will occur when a person is touching the touch pad 30 at the same time that he is touching the ignition key, the ignition key completing the circuit to earth. If the ignition key is covered with an insulating material such as plastics it may be provided with an exposed metal portion for contact by the user. Such an exposed metal portion may comprise a rivet or other fastener. Alternatively, one may touch the touch pad 30 and another earth in the vehicle such as a metal trim strip and this will place the circuit 22 in an active mode so as to enable the ignition switch 20 to be operated to start the vehicle engine. In yet an alternative arrangement, an earth point or terminal may be located adjacent to the touch pad 30 so that a finger of a user may span both creating the circuit between the touch pad 30 and earth. The touch sensitive switch circuit 29 may be provided with an override facility in the form of a switch which will connect the touch pad to earth, furthermore a pair of spaced apart touch pads or terminals 30 may be provided in place of the single touch pad 30. A switch also may be provided to enable selection of the pad 30 which will cause actuation of the circuit. As stated above the control circuit 22 incorporates in a preferred form a microprocessor and MOSFET switches. The microprocessor however, may be replaced by a hardware wired control circuit with the MOSFET switches replaced by relay operator switches. Whilst the preferred security system 21 suitably incorporates a touch switch circuit 29 as described and illustrated, the system may include remote actuating means such as an infra red or ultrasonic or radio wave remote actuating system in place of the touch switch circuit 29 so that the system can be operated remotely. The security system 21 may additionally include a door opening sensitive circuit 31 which includes the door switches 32 as normally incorporated in a vehicle door pillar actuated when a door is open to actuate courtesy or interior lights within the vehicle. When the vehicle is operating with the engine 10 running, and if one of the doors is opened, the corresponding switch 32 will be actuated. This will be sensed by the microprocessor 23 and after a set time delay, for example thirty seconds, the microprocessor 23 will cause the switch 25 to close to thereby suppress the management system data signals. This will immediately cause the engine 10 to stop operating. Additionally, the engine 10 will not be able to be restarted unless the touch pad 30 is again touched in the manner described above to open the switch 25 and close the switch 24. The anti-carjacking circuit, could of course be used with forms of security systems other than that described above. This circuit also preferably includes an override switch which enables the circuit to be disconnected or overridden which can be used at the owners discretion. Whilst the above has been given by way of illustrative embodiment of the invention, all such modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of the invention as herein defined in the appended claims.

Claims: CLAIMS 1. A security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said security system including control circuit means having first and second states, said control circuit means in said first state inhibiting operation of said management system so as to prevent operation of said engine, control means for causing said control circuit means to be placed from said first state into said second state, said circuit means in said second state enabling operation of said management system thereby allowing operation of said engine. 2. A security system according to Claim 1, wherein said management system has at least one data input line, said security system being connectable to said input line such as to suppress or corrupt data on said input line in said second state of said control circuit means. 3. A security system according to Claim 2, wherein said input line receives timing data of said engine. 4. A security system according to Claim 1, wherein said management system includes at least one data output line and wherein said security system is connectable to said data output line, said control circuit means in said second state suppressing or corrupting data on said data output line. 5. A security system according to Claim 4, wherein said at least one data output line is connected to an igniter associated with the spark plugs of said engine. 6. A security system according to Claim 4, wherein said at least one data output line is connected to fuel injectors for said engine. 7. A security system according to Claim 1, wherein said control circuit means includes first switch means, said switch means being connectable to one of said data lines, said switch means being closed in said first state of said control circuit means to suppress the data on said data lines. 8. A security system according to Claim 7, wherein said first switch means is connected through capacitance means to a supply line, in said first state of said control circuit means said capacitance means suppressing said data in said data lines in said first state to prevent starting of said engine by hot-wiring. 9. A security system according to Claim 1, wherein said control means includes a touch sensitive switch circuit, said touch sensitive switch circuit being responsive to touching to cause said control circuit means to be placed from said first state to the second state. 10. A security system according to Claim 9, wherein said control circuit means is only placed from said first to said second state if said touch sensitive switch circuit is activated for a predetermined time. 11. A security system according to Claim 9 or Claim 10 wherein said touch sensitive switch circuit includes a touch pad or terminal located within said vehicle. 12. A security system according to Claim 1 and including means associated with at least one door of said vehicle to sense opening thereof, said means being operable to cause said control circuit means to be placed from said second state to said first state to prevent operation of said engine. 13. A security system according to Claim 9, wherein said door opening sensing means includes at least one switch means, said switch means being actuated upon opening of said door and wherein said control circuit means is placed into said first state a predetermined time after actuation of said door opening sensing means. 14. A security system according to Claim 1, wherein said control circuit means includes second switch means, said switch means preventing supply to the starter of said engine in said first state of said control circuit means but permitting supply thereto in said second state. 15. A security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said management system having a plurality of data lines, said security system including control circuit means connectable to at least one of said data lines, said control circuit means in a first state suppressing or corrupting information on said at least one of said data lines to prevent operation of said engine and touch sensitive circuit means operable to cause said control circuit means to be placed from said first state into a second state, said control circuit means in said second state permitting data to flow along said data line to thereby permit operation of said engine. 16. A security system for use with a vehicle of the type having an internal combustion engine and a management system for controlling the operation of said engine, said security system including control circuit means having first and second states, said control circuit means in said first state inhibiting operation of said management system so as to prevent operation of said engine, said circuit means in said second state enabling operation of said management system thereby allowing operation of said engine, and means for sensing opening of a door of said vehicle to cause said control circuit means to be placed in said first state to prevent operation of said engine.

Inventors: JACKSON PAUL STANLEY, MCDONALD WALTER GILBERT, VIDMAJER BORIS, JACKSON, PAUL, STANLEY, MCDONALD, WALTER, GILBERT, VIDMAJER, BORIS
Applicants: JACKSON PAUL STANLEY, MCDONALD WALTER GILBERT, VIDMAJER BORIS, JACKSON, PAUL, STANLEY, MCDONALD, WALTER, GILBERT, VIDMAJER, BORIS
Application year: 1994
Main classification: F02P11
IPC codes: B60R25, F02P11